As a twin, people have a lot of questions. I’ve lost count of how many times I’ve been asked if I possessed a telepathic connection with my twin (sadly, I don’t). And I’d rather forget the numerous moments when I’ve been asked if I’m identical to my twin BROTHER (gladly, I’m not). But, most of all, I’ve been asked that million-dollar question: do I share an unbreakable twin-bound bond with him? Without thinking twice, I’ll always say: yes.

You see, the thing is, my twin and I were side-by-side throughout our formative years. In our baby cot we lay back-to-back, night after night. In primary school we sat right next to each other (at my parents’ request) during every lesson. Then, in high school, we attended most classes together – and without fail we’d be with one another during every break as we ate our packed lunches. We even shared the same friendship circle. And, so it made sense that, without even meaning to, we ended up studying at the same university in Scotland, too.

Then, at the age of 23, he left for Aberdeen; and two years later, I flew off to the Middle East.

Now, fast forward five years later and I’m in London. And in a few months’ time he will be, too. Our lives may have gone in different directions for a period, but our strong connection has never changed nor suffered.

And psychology backs these unique feelings up

It’s this hard-to-describe twin connection that has led celebrities Mary-Kate and Ashley Olsen to compare being a twin to a marriage.

“It’s been 32 years of learning how to communicate,” Ashley said of their relationship in a recent (and rare) interview with WSJ. She added that their bond felt like being in “a marriage and a partnership” and said, “we have had ups and downs… we do everything together.”

“We came out of the womb doing that,” Mary-Kate joked alongside her.

Here’s the truth: they’re right. And I applaud them for admitting it.

Don’t get me wrong, I also have great relationships with both of my other siblings. But as most siblings do, we argue, fight and squabble. But my relationship with my twin is different. We never argue. We always back each other up, no matter what. It’s like we’ve formed some kind of language and understanding that no-one else shares (nor would we ever let them). He’s my ‘Twinny’ and my true best friend for life.

And, it’s not just us. Science and psychology backs up these unique feelings.

“Twins are born married, therefore the twin bond is much more intense than the sibling bond,” Barbara Klein, a psychologist and specialist on the development of twin identity, tells Stylist.co.uk.

“Twins become relationship experts as their ‘marriage’ develops from youth”

It is an intense bond, but competitiveness or constant fighting is definitely not something I would attribute to my twin and I’s relationship. Thankfully, we’re very different. Not only do we work in different fields, but we also have different outlooks on life. For one, he’s motivated by money – but I need passion.

But being classified as a ‘pair’ from a young age has had a part to play in the bond that’s subsequently formed between us – and some other twins, too. Because, ultimately, twins become relationship experts as their ‘marriage’ develops from youth.

“By the time they’re one or two, they’re like an old married couple,” writer Patricia Malmstrom explains in her book The Art of Parenting Twins. “They fight, but they love each other. They know that they have to live together.”

Twins become relationship experts as their ‘marriage’ develops from youth

Maybe that’s why we don’t pine for a significant other as some people do. Unlike the rest of our friends, being in a relationship has never been at the top of either of our priority lists. According to a study carried out in 2012, researchers found overall lower marriage and divorce rates in twins compared to non-twins. One reason cited is because twins “do not have the same need for marriage as singletons, but have more experience in maintaining a relationship if they do marry”.

However, learning (very quickly) how to live together, and enjoying doing so, can make it difficult for other relationships to find solid ground. This is something that Stylist’s Deputy Editor, Gemma Crisp – who has a twin sister – knows all too well.

“My husband says he knew when we got together that he was getting a ‘package deal’ – he didn’t just get me coming into his life, but my twin sister too,” Crisp explains. “And [he knew] that she would always be a priority, no matter what.”

It was only after being together for four years that Crisp’s husband delivered an honest demand.

“He had to give me an almost-ultimatum to force me to move in together because I didn’t want to stop living with her,” she says.

“When people ask if we’re close, I tell them that I would kill for her. That’s how much she means to me and how far I would go for her.”

But not all twins feel this way. In fact, some feel like coming into the world as a pair had a detrimental effect on their relationship from day one.

“The twin connection is a tough act to follow – and one that should be cherished. ”

“People always expect my twin brother and I to be extremely close,” says Kate*, 26. “But actually, we have quite a difficult relationship, something that I think has a lot to do with us being twins. People would often compare our personalities and achievements when we were younger - which I don’t think they’d have done as much if we were just ‘normal’ siblings - and we spent a lot of time in one another’s space.

“As a result, my brother ended up feeling quite overshadowed and resentful of me. We’re still dealing with the repercussions of that dynamic today.”

Friction between twins could be due to each individual person struggling to separate themselves from their twin as they grow up.

“Twins share the same toys, clothes, home life and school, therefore developing an individual identity is harder for them,” explains Klein.

“Often comparison and over-identification with one another creates serious fighting and shame which non-twins do not experience, even if they are very competitive.”

Accounting for just 3% of the world’s population, twins – like Mary-Kate and Ashley – are brave to admit they feel “married”. But it’s a connection that’s a tough act to follow – and one that should be cherished.